Low-temperature mechanochemical-thermal synthesis of {alpha}-Al{sub 2}O{sub 3} nanocrystals
- Faculty of Natural Sciences, Comenius University, Mlynska Dolina, SK-842 15 Bratislava (Slovakia)
- Kadan Ltd., Lapaska cesta 458, 951 02 Pohranice (Slovakia)
- Faculty of Materials Science and Technology, Slovak University of Technology in Bratislava, Paulinska 16, SK-917 24 Trnava (Slovakia)
- Chemical Institute, Faculty of Natural Sciences, Comenius University, Mlynska dolina, 842 15 Bratislava (Slovakia)
Highlights: {yields} Polyaluminium chloride as {alpha}-Al{sub 2}O{sub 3} precursor was obtained by simple dissolution of Al rods in hydrochloric acid. {yields} A facile low temperature synthesis of {alpha}-Al{sub 2}O{sub 3} was obtained from 10 min high-energy ball milled and annealed polyaluminium chloride. {yields} {approx}15 nm {alpha}-Al{sub 2}O{sub 3} nanocrystals emended in amorphous alumina matrix were prepared at temperature as low as 400 {sup o}C. {yields} Gradual {alpha}-Al{sub 2}O{sub 3} formation up to 1000 {sup o}C was obtained. {yields} 50 nm {alpha}-Al{sub 2}O{sub 3} nanocrystals were obtained after annealing at 1000 {sup o}C. -- Abstract: The great capability of high-energy ball milled basic polyaluminium chloride gel (PACl) which consisted of the monomeric Al{sup 3+} ions and polymerized Al{sup 3+} species such as [Al{sub 13}O{sub 4}(OH){sub 24}(H{sub 2}O){sub 12}]{sup 7+} with a Keggin like structure to enhance the phase transformation into {alpha}-Al{sub 2}O{sub 3} nanocrystals at low temperature was verified. PACl gel 10 min milled and annealed at 400 {sup o}C, partially transformed to nanocrystalline {alpha}-Al{sub 2}O{sub 3} with the mean XRD crystallite size in the range of 15-17 nm, embedded in an amorphous or transition alumina matrix. Further crystal growth up to {approx}50 nm and phase pure {alpha}-Al{sub 2}O{sub 3} powder was obtained when heat-treated at 1000 {sup o}C. In contrast to this, the non-milled PACl gel transforms to the transition {theta}-Al{sub 2}O{sub 3} phase at 1000 {sup o}C. The evolution of {alpha}-Al{sub 2}O{sub 3} nanocrystals was studied by XRD, TEM, selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) methods.
- OSTI ID:
- 22210140
- Journal Information:
- Materials Research Bulletin, Vol. 46, Issue 11; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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